The chemical oxygen-iodine laser (COIL) is undergoing development as the high-performance laser of choice for target interdiction. In this laser, a supersonic flow of singlet delta oxygen is used with iodine as the gain medium in the laser cavity of a continuous wave (cw) chemical laser. A chemical gas laser according to the invention involves a steady, supersonic, low-pressure gaseous flow inside the laser cavity. In fact, all high-performance cw chemical lasers operate supersonically with a laser cavity pressure of a few Torr. For example, a COIL typically operates in the 1 to 10 Torr range, although pressures as high as 20 Torr may be possible. A pressure value above about 4 Torr is usually achieved by adding diluent gas to the singlet oxygen generator (SOG) that drives the COIL device. A diffuser is then used to increase the device's exit pressure. If this pressure is still below ambient, the diffuser is followed by a pumping system that typically consists of mechanical pumps or an ejector system. (In specialized cases, chemical pumping may be used.) The type of high-performance laser under consideration may potentially be mounted on a motorized vehicle, naval vessel, or on an aircraft. It requires a pressure recovery system to move the high-speed, spent laser gas from its several Torr value to a pressure level slightly above ambient. At sea level, ambient is 760 Torr, while ambient for an aircraft at a 40,000 foot altitude would be close to 150 Torr. Thus, due to the pressure differential, pressure recovery presents a challenge. In any case, the size and weight of the pressure recovery system is significant to the viability of the overall laser system. It is thus important that the pressure recovery system be as compact and lightweight as possible for the intended application.
In a laboratory, mechanical pumps are used for pressure enhancement, but these are certainly not compact or lightweight. Outside of the laboratory, ejectors are typically utilized. The ejector system, however, may require multiple stages and is both bulky and heavy. In special cases, where the laser run time and power are limited, a bulky chemical pump system can be used.
Accordingly, there is a need for a relatively compact or lightweight pressure recovery system for increasing the pressure of a gas used in a chemical oxygen-iodine laser so that the gas may be brought to ambient pressure.